1. Field of the Invention
The present invention relates to an alkaline storage battery which includes a bottomed cell casing assembled as either one of negative and positive terminals, a closure cap assembly coupled in a liquid-tight manner with an opening of the cell casing as the other terminal to hermetically seal the interior of the cell casing and a generator element composed of positive and negative electrodes assembled within the cell casing. More particularly, the present invention is concerned with a current collecting structure of the generator element and a method of welding a positive current collecting plate extended from either one of the positive and negative electrodes to a bottom surface of the closure cap assembly.
2. Description of the Prior Art
In a conventional alkaline storage battery such as a nickel-cadmium storage battery, a nickel-hydride storage battery or the like, positive and negative electrode sheets are spirally wound through a separator sheet into a cylindrical body to provide a generator element. The generator element is contained in a metallic cell casing, and a positive current collecting plate extended from the positive electrode sheet is welded to a bottom surface of a closure cap assembly. Thereafter, the closure cap assembly is coupled with an opening of the cell casing through an insulation gasket to hermetically seal the interior of the storage battery.
In use of the alkaline storage battery as an electric power source in an electrically operated tool, an electric bicycle or an electric motor cycle, there is a concern that the current collector plate will become removed from the closure cap assembly due to vibration applied thereto. To avoid such removal of the current collecting plate, it is required to enhance the vibration resistance property of the storage battery. In such use of the alkaline storage battery, it is also required to reduce internal resistance of the storage battery for discharge of a large amount of electric current.
In the conventional alkaline storage battery, however, the current collecting plate is welded only at one portion to the bottom surface of the closure cap assembly. For this reason, the vibration resistance property of the storage battery is insufficient, and the internal resistance of the storage battery may not be reduced.